Attorney General Eric Holder says outgoing FBI Director Robert Mueller set the standard for leading the agency during the last 12 years.

At a farewell ceremony at the Justice Department Thursday, the attorney general said Mueller led a historic transformation of the FBI by redefining it as an intelligence-driven agency. Mueller, who steps down next month, has run the FBI since a week before the Sept. 11, 2011 attacks. Holder credited Mueller with thwarting some of the most serious terrorist plots the U.S. has faced since then.

Holder presented Mueller with the Attorney General’s Award for Exceptional Service — the highest award the attorney general can bestow within the Justice Department.

On Monday, the Senate confirmed James Comey to succeed Mueller.

(AP)